1. Field of Invention
The present invention relates to a pump that is capable of releasing excessive air.
2. Related Prior Art
Taiwanese Patent Publication No. 446070 teaches an upright pump including internal and external cylinders. This conventional pump includes a base 10, an internal cylinder 20 mounted on the base 10, a piston 43 movably received in the internal cylinder 20, a rod 41 connected with the piston 43, an external cylinder 50 mounted on the internal cylinder 20, a pressure gauge assembly 70 mounted on the external cylinder 50 and a nozzle 90 in communication with the pressure gauge assembly 70 through a pipe 80. The internal cylinder 20 defines a space 22 and an aperture 25 at a lower end in communication with the space 22. A space 52 is confined between the internal cylinder 20 and the external cylinder 50. The space 22 is in communication with the space 52 through the aperture 25. The external cylinder 50 defines an aperture 53 near an upper end. The pressure gauge assembly 70 is located at the upper end of the external cylinder 50. A space defined in the pressure gauge assembly 70 is in communication with the spare 52 through the aperture 53. In pumping, pressurized air flows from the space 22 to the space 52 from which the pressurized air flows to the space defined in the pressure gauge assembly 70 through the aperture 53. Although this conventional pump is equipped with the pressure gauge assembly 70, a user may still over pump, for example, a tire with it. When this happens, it is better for the user to release air from the tire. Such releasing excessive air from the tire is not possible unless the nozzle 90 is removed from a valve of the tire. Such removal of the nozzle 90 from the valve of the tire is however inconvenient. What is worse, the user does not know if he or she releases too much air from the tire unless he or she engages the nozzle 90 with the valve of the tire again. This renders precise pumping more difficult.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.
It is the primary objective of the present invention to provide a pump that is capable of releasing excessive air.
According to the present invention, a pump capable of releasing excessive air is shown to include a hollow base, a cylinder installed on and communicated with the hollow base, a piston movably received in the cylinder, a piston tube including a lower end connected with the piston and an upper end located beyond the cylinder, a tube including a lower end communicated with the hollow base and an upper end inserted into the piston tube through a channel defined in the piston, a release valve mounted on the upper end of the piston tube and a handle mounted on the upper end of the piston tube. The valve is installed on the handle so that it can be touched conveniently and operated easily by a user who is using the pump.
Other objectives, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the attached drawings.